Production of sugar cane wax



Filed March 14, 1947 PRESS RESIDUE SUPPLIED FROM SUGAR CANE MILLS.

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Q Y E T N m w F P W E A O G Cl E N R E Patented July 26, 1949 PRODUCTIONOF SUGAR CANE WAX Werner F. Goepfert, Short Hills, N. J., assignor toInterchemical Corporation, New York, N. Y., a corporation of OhioApplication March 14, 1947, Serial No. 734,626

3 Claims.

This invention relates to the recovery of the hard wax found in thefilter residues which are obtained in extracting sugar cane and aims toimprove a method for recovering from such residues high yields of a hardwax which is an acceptable substitute for carnauba wax.

In my Patent No. 2,391,893 of January 1, 1946, I have disclosed a rapidand economical one-step method for recovering such hard wax from filterpress residues of sugar cane, by extracting the residues with suitablesolvents at elevated temperatures, in a ratio of not less than fourparts of solvents to one part of residue (the ratio based on the dryweight of the residue) and separating from the extract, by means ofchilling, that portion of extracted matter which consists of the hardwax, while the simultaneously extracted fatty constituents of the filterresidue remain in solution.

The object of the present invention is an improvement in the process ofextracting the said hard wax and this improvement is based on thediscovery that the amount of solvent, necessary for the extraction of agiven quantity of filter residue, can be materially reduced if thelatter, prior to the extraction, is compressed and dried so as to formcoherent masses which substantially retain their coherency throughoutthe subsequent procedures. I found that, after compressing and dryingthe filter residue in this manner, whereby its apparent density(compared in the dry state) is approximately doubled, only aboutone-fourth of the previously required amount of solvent is needed,without impairing the efficiency of the extraction and that the amountof solvent remaining absorbed in the extracted residue is similarlyreduced. In my preferred procedure, the residue is compressed into rodsof a diameter of about one-quarter of one inch. Upon leaving theextrusion press, these rods may break into segments of various lengths.I wish to emphasize, however, that it is the step of compressing alonewhich permits the subsequent saving on solvent, irrespective of the formand, within certain limits, irrespective of the size which the particlesmay attain thereby. The results will be the same if the material iscompressed into particles having hexagonal cross sections or into barshaving a width of, say, up to one-half of one inch.

It is the more surprising that the increased density does not impair theextraction since it is ordinarily thought that a more finely dividedmaterial is extracted more easily; an assumption which I found not to betrue in this case.

Several. important procedural changes become possible in consequence ofthis discovery. The filter residue or mud (as it is frequently called),leaves the filter presses at the cane sugar mills with a moisturecontent of about per cent and is rather bulky for this reason. Inasmuchas it contains, besides other growth supporting substances, smallamounts of sugar, it constitutes an effectual medium for bacterialpropagation and, for this reason, cannot be stored for any length oftime without deteriorating. But if the mud is compressed into coherentparticulate form and dried thereafter, its weight and bulk are not onlyreduced to less than half but it may now safely be storedfor any lengthof time.

Whenever wax is to be extracted from moist filter residue, in view ofthe rapid deterioration and putret'aetion of the undried material, theextraction must be carried out concurrently with the cane sugar campaignof the sugar mills from which the mud is obtained. It is significantthat the drying of the mud renders the extraction process independent ofthe time of harvesting and crushing of the sugar cane and that itenables a continuous operation of the extraction facilities, provided asuflicient quantity of the dried residue has been accumulated andstored.

Aside from the social factor of procuring steady employment if theextraction of wax from the dry mud is extended over the larger part ofthe year with, perhaps, the only interruption of switching the operatorsto the drying of the mud during the relatively short cane sugarcampaign, the economic gains in the wake of the aforementioned discoveryare most noteworthy. Since the capacity required of the extractionequipment, for the production of a given quantity of wax, will change inan inverse ratio with the length of time during which the equipment canbe utilized, the possibility of spreading the production over the;entire year reduces the required unit size to less than one-fourth ifthe originally planned production volume is to be maintained, or,conversely, increases more than four fold the capacity of a unit whichhad been designed for seasonal operation. It is important that thisreduction of the relative costs of installation permits a decidedly moreprofitable use of capital.

expenditures while a continuous operation tends to reduce the costs ofdepreciation. In view of the fact that the margin between gain and lossin the extraction of sugar cane wax is necessarily a narrow one, largelydepending upon. the degree of efficiency of operation and inasmuch assolvent losses represent a major item in the pro- 3 duction costs, theeconomical import of my discovery is self-evident.

Referring to the drawing, in practicing my invention a plant for theextraction of sugar cane wax (which should, if possible, be centrallysituated relative to a number of sugar mills supplying the filter pressresidue), consists of two main parts: a seasonall run dryinginstallation and a continuously operated extraction assembly. At thesugar mills the cane is shredded and crushed between rollers to extractthe juice which, at this stage, consists of a dark, opaque liquid,carrying, besides other solids, part of the wax from the canes insuspension; In order to remove these suspended solids and'to precipitatecolloidal matter which is present, the juice is limed, heated, and, as arule, clarified by sedi- V mentation in tanks from where the clearsupernatant liquid is drawn off. The final sediments are concentrated infilter presses. These residues leavethe presses with a moisture contentof about 60 to 70 per cent and are reduced, preferably at the mills, toa moisture content of about 40 per cent (which may easily beaccomplished by means of a dewaterer 12); not only in order to reducethe'mud in weight and volume prior to its transfer to the extractionplant, but mainly because it was found that a moisture'content ofroughly 40 per cent is required for compressing the mud into coherentparticles which are essential for the subsequently claimed saving onsolvent. A moisture content within the range of, say, 35 to 45 per centwill generally be found optimal for this purpose, although a propercompressing will depend upon a number of secondary factors, such as therelative amount of sugar, gums, and other constituents of the mud-whichact as binders, upon the type of equipment, the temperature, pressure,etc. The operation may be performed by means of a suitable extrusionpress I 3. The resulting mud particles are then dried to 2, moisturecontent of about two per cent, which may be done either by means of avacuum drier M, or with a blower type drier at atmosphericpressure,whereby, however, temperatures above 185? 4 wax is separated from thesolution b means of a filter 23 and the solution is transferred to anevaporator 24 in order to recover therefrom the fatty constituents,which are collected in storage 25. Since this so-called soft fractionrepresents about 30 to 45 per cent of the totally extracted matter andsince it consists in the mainof glycerides of fatty acids, such aspalmitic, stearic and oleic acid, of various sterols of the phytosterolclass and of resin acids, pectins and chlorophyll, the soft fractionprovides a valuable byproduct. The solvent which is evaporated in thisoperation, after passing a condenser 26, is sent to the solvent storagetank I6. Having freed, in the meantime, in drier 21 the hard wax fromthe remaining solvent (whereby the vapors of the latter are precipitatedin condenser 28 and are also recycled to storage tank It) it isrecovered,

' depending upon the manner of drying, either in F. should be avoidedin. order not to impair the:

wax and its subsequent extracting. The material is placed, after drying,in storing facilities 15 from where adequate amounts are removed asneeded for the extraction. 7

Having charged anextractor l! with a given quantity of dry mudparticles, about one and one-half times its weight of a suitable solventis drawn from a solvent storage tank I6 and the mud is digested, at atemperature preferably approximating or approaching the boiling point ofthe solvent, for a sufficient period of time to in-, sure .completesolution of the waxy and fatty constituents of the mud. The solution isthen separated, by means of a filter I 8 or any other suitable means,and the mud transferred to an evaporator 19, where it is freed, ascompletely as possible, from the absorbed solvent, whereby the vapors,after having been reduced to the liquid stage in a condenser 20, arerecycled to the solvent storage tank is. The remaining exhausted mud,collectedin storage bin 2|, may be used for any suitable purpose, suchas fuel, fertilizer, or as a filler. f

The solvent, containing thewaxy and fatty matter, has been'transferred,in the meantime, to a cooling tank 22. There it is chilled to about 15C. whereby the so-called hard wax precipitates in granular form whilethe extracted fatty material remains in solution. The precipitated formof the little granules at which it has. been precipitated in coolingtank '22, or' in form of a melted product if dryer 2! is operated at asufliciently high temperature; A typical product, taken from storage 29,analyzes as follows:.melting point 75 to 78 C., acid number25-30,saponification number 50 to 60, iodine number 30 to 35, acetyl number 10to 15;

Whereas the above description deals with batch operations, it is obviousthat a continuously operating extraction assembly will result in stillgreater efficiency and in additional savings.

As disclosed in my co-pending application, Serial No. 589,273,'fi1edApril 19, 1945, now Patent No. 2,430,012, among the solvents which maybe used are acetone, methyl ethyl ketone, methyl isobutyl ketone, methylamyl ketone, diisopropyl ketone, and methyl, ethyl, propyl, butylfandamyl acetates and propionates. Of the solvents, I prefer to use thosehaving boiling points not in excess of C. since I find that the solventshaving a higher boiling point are somewhat more difiicult torecover-from the wax, and that discoloration of the wax may occur withthem un less great care is taken in the recovery operation;

.For such subject matter as is common to, my copending applicationSerial No.- 589,273, filed April 19, 1945, I claim the benefit of thatdate.

I claim:

1. In the extraction'of wax from sugarcane mud by an organic waxsolvent, the improvedstep of preparing the mud for extraction whichcomprises compressing mud, dewatered to a moisture content of 36 to42per cent by weight, into rod-like, coherent masses, and dryingsaidmasses at a temperature below whereby the wax may be extracted with afraction ofthe amount of solventnecessaryfor the extraction of dried mudnot compressed in the said manner;

2. In the extraction of wax from sugar cane mud by an organic waxsolvent, the improved step of preparing the mud for extraction whichcomprises dewatering thewet mud to a moisture content between 36 to 42per cent by weight, com-r pressing the mud into coherent masses long in"one dimension and of a cross section in the short dimension not aboveone-half of one inch,'and drying said masses at. a temperature below 150F. to a moisture content of about two per cent, whereby the wax may beextracted with less than 40 per cent of the amount of solvent nec'essaryforthe extraction of dried mud not compressed in the said manner.

3. In the extraction of wax from sugar cane mud by an organic waxsolvent, the improved step of preparing the mud for extraction whichcomprises compressing mud, dewatered to a REFERENCES CITED moisturecontent of 36 to 42 per cent by weight into coherent masses long in onedimension and of a cross section in the short dimension not above Thefollowing references are of record in the file of this patent:

one-half of one inch, and drying said masses at 5 UNITED STATES PATENTSa temperature below 150 F. to a moisture con- Number Name Date tent ofabout two per cent, whereby the wax may 2 381 420 Balch Aug 7 1945 beextracted with less than 40 per cent of the 2391:893 Goepfefi 1946amount of solvent necessary for the extraction of dried mud notcompressed in the said manner. 10

WERNER F. GOEPFERT.

